Retinol and pro-retinol (aka retinoids) are the key to young-looking skin. That, at least, is the conclusion of a study reported yesterday in the journal Archives of Dermatology.

The research, undertaken at the University of Michigan Medical School, found that over a period of 24 weeks skin treated with “a retinol cream” compared favourably to skin treated with an ordinary moisturiser.

Even as I write, women all over Britain will be dashing to their nearest department store to stock up on something – anything – that contains the stuff. Because there is nothing that clouds a woman’s judgment more (except, perhaps, for a large slab of Green & Black’s almond milk chocolate and a photograph of Brad Pitt) than the prospect of a Cure for Wrinkles. Look what happened when the BBC recommended No 7 Protect & Perfect in its Horizon programme last month: sold out in hours.

I was sent a preview tape of that Horizon programme at the end of last year, and watched it as part of my general remit as beauty editor for the Times Magazine. Afterwards I bought a bottle of Protect & Perfect and tried it for myself. As always, my intention was to use it for a month (you should always give a new cream a month before you judge the effects, as that is the rough duration of the skin’s renewal cycle); in fact I had to give it up after a fortnight. My skin had become irritated and dehydrated, and I had even developed some dry patches.

This is not to say that P&P is not a perfectly good product; it simply was not the right one for my skin. But it does illustrate a problem with stories such as that one and this latest about retinol: too much hype and gross generalisation.

In the case of the retinoids story, none of the press reports that I read specified the concentration of retinol used in the cream. The original article, which can be found on the internet, states: “Topical 0.4 per cent retinol lotion or its vehicle was applied at each visit by study personnel to either the right or the left arm, up to three times a week for 24 weeks.”

Also, the test was carried out on arms rather than faces. This is a vital distinction, as most women are concerned primarily with signs of ageing on the face. And what is the main cause of premature facial ageing? Sun damage, of course. What is the point of a rejuvenating cream (I won’t say “anti-ageing” because it’s a ridiculous expression) that doesn’t work on your face?

The beauty market is awash with products containing retinol. Some may be right for you; some may not. The only way to find out is trial and error.

If you are serious about doing the best for your skin, don’t rely on a cocktail of money and hope. Consult an expert – by which I don’t mean the girl in Boots or, for that matter, me. See a dermatologist. If you thought that you might have appendicitis, you wouldn’t ask your hairdresser’s opinion, would you? So why rely on the say-so of a sales assistant, however well-intentioned, for a diagnosis of your skin problems? Likewise, I can offer general tips and advice but for an expert opinion, ask a professional.

Emma Edmonds, a dermatologist for the British Skin Foundation (020-7383 0266, and an excellent source of sober, sensible skin advice) says that the exact mode of retinoid action is unknown. What is known is that retinoids increase cell turnover in the skin. The concentration in medical creams prescribed by dermatologists is usually 0.025 per cent. There are some downsides: they can make the skin red, sore, flaky and irritated (obviously what happened to me with P&P). On darker skins they can sometimes cause an increase in pigmentation.

Retinoids have many names but essentially they are Vitamin A derivatives and their success is not especially new – dermatologists have been using them for a long time, in particular to treat acne scarring.

Professor John Hawk, also a dermatologist, adds: “Since most skin ageing is gradually produced over the years, even on cloudy or cool days, by middle-of-the-day sun exposure and by smoking, it is far better to cover up or use a sunscreen and not smoke.”

Times recommends

• Live chat: Thrifty ways to update your winter wardrobe
• Is anybody out there really listening?
• Nutrition Q&A: Will eating late make me fat?